Rolling bearing device with sensor

Abstract

To provide a rolling bearing device with a sensor capable of reducing size in a bearing axis direction, which is a width direction of a drive wheel, and having excellent handleability.SOLUTION: A rolling bearing device with a sensor comprises: an angular contact ball bearing unit 30, composed of a double-row angular contact ball bearing or a plurality of angular contact ball bearings, which comprises an outer ring 31 having a raceway surface 31a on an inner peripheral surface, an inner ring 32 having a raceway surface 32a on an outer peripheral surface, and a plurality of balls 33 disposed so as to freely roll between the raceway surfaces 31a, 32a of the outer ring 31 and the inner ring 32, and which is used for outer ring rotation; an encoder 72 fixed to the outer ring 31 radially outside of the outer ring 31; and a magnetic sensor 76 which is fixed to the inner ring 32 via a fixed-side bracket 75 radially outside of the outer ring 31 so as to face the encoder 72, and detects the rotational speed of the outer ring 31.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sensor-equipped rolling bearing device, and more particularly to a sensor-equipped rolling bearing device that can be used in an in-wheel motor applied to the drive wheel of a traveling robot. [Background technology]

[0002] Recently, not only are autonomous mobile robots used for transporting goods within factories, but last-mile robots that can travel outdoors are also emerging. As of 2023, the Road Traffic Act stipulates that mobile robots traveling on public roads (sidewalks) must be 120cm long, 70cm wide, and 120cm high, in order to avoid obstructing pedestrian traffic, which places very strict size restrictions on them.

[0003] Patent Document 1 discloses an in-wheel motor that can be miniaturized while incorporating an angle sensor, by fixing a shaft to one of a stator and a rotor and arranging an angle sensor between the axial end of the shaft and a portion of the other of the stator and rotor that faces the end.

[0004] Furthermore, Patent Document 2 discloses an in-wheel motor in which the rotor is supported by a stator at both ends in the wheel width direction, thereby achieving a compact motor and stable driving performance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-185975 [Patent Document 2] Japanese Patent Application Publication No. 2023-90230 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, the Road Traffic Act places strict size restrictions on traveling robots, and to overcome these restrictions and ensure traveling stability, further miniaturization is required for the in-wheel motors that are installed in the drive wheels and serve as the driving sources for traveling robots. For this reason, miniaturization is also required for the sensor-equipped rolling bearing devices that are used in in-wheel motors and that are equipped with encoders and sensors.

[0007] On the other hand, when reducing the size of an in-wheel motor, the following problems can be considered. (A) Because the drive wheels are subjected to vertical loads and moment loads, it is desirable to install multiple bearings, which makes it difficult to reduce the width. (B) The shaft's fastening surface is small, which causes excessive surface pressure with the vehicle mounting bracket, resulting in insufficient connection strength with the vehicle body. (C) A hollow shaft is used to route the wire harness around the vehicle body, but the inner ring of the bearing is pressed in to support the specified load, so there are strict restrictions on the inner and outer diameters of the shaft. (D) Autonomous robots require precise position control, and a sensor with a resolution equal to the number of poles in the motor magnet may not have sufficient resolution. While it is possible to increase the resolution by installing an MR sensor at the tip of the shaft, this requires additional space in the width direction.

[0008] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a sensor-equipped rolling bearing device that can be made smaller in the bearing axial direction, which is the width direction of the drive wheel, and is easy to handle. [Means for solving the problem]

[0009] The above object of the present invention is achieved by the following configuration [1] relating to a sensor-equipped rolling bearing device. [1] An angular contact ball bearing unit comprising an outer ring having a raceway surface on its inner circumferential surface, an inner ring having a raceway surface on its outer circumferential surface, and a plurality of balls arranged to roll freely between the raceway surfaces of the outer ring and the inner ring, and used for outer ring rotation, comprising a double-row angular contact ball bearing or a plurality of angular contact ball bearings; an encoder fixed to the outer ring on the radially outer side of the outer ring; a magnetic sensor fixed to the inner ring via a fixed-side bracket radially outward of the outer ring so as to face the encoder, and configured to detect the rotational speed of the outer ring; Rolling bearing device with sensor. [Effects of the Invention]

[0010] According to the present invention, the encoder and the magnetic sensor can be handled as one unit with the angular ball bearing portion, which makes it possible to achieve a smaller size and improve ease of handling. Furthermore, when applied to an in-wheel motor, the width of the in-wheel motor can be slimmed down, making it possible to miniaturize the running robot, preventing collisions with pedestrians and contributing to the spread of running robots. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an exploded perspective view of an in-wheel motor equipped with a sensor-equipped rolling bearing device according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the in-wheel motor shown in FIG. [Figure 3] Fig. 3(a) is a top view of a running robot in which an in-wheel motor according to the present invention is mounted on a wheel, Fig. 3(b) is a side view of (a), Fig. 3(c) is a top view of a running robot in which a conventional in-wheel motor is mounted on a wheel, and Fig. 3(d) is a side view of (c). DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of an in-wheel motor equipped with a sensor-equipped rolling bearing device according to the present invention will now be described in detail with reference to the drawings. The in-wheel motor according to this embodiment is a direct drive in-wheel motor suitable for use as a drive wheel of a self-propelled robot, a transport vehicle, or the like.

[0013] As shown in Figures 1 and 2, the in-wheel motor 10 includes a support shaft 20 fixed to a vehicle body (not shown) such as a self-propelled robot or a transport cart via a vehicle body mounting bracket 11, a double-row angular ball bearing 30 as an angular ball bearing part fitted and fixed to the outside of the support shaft 20, a stator 40 similarly fitted and fixed to the outside of the support shaft 20 in line with the axial direction, and a rotor 50 arranged on the outer diameter side of the stator 40 so as to be rotatable concentrically with the stator 40.

[0014] The support shaft 20 is a pipe-shaped member having a through hole 21 formed at its axis and penetrating in the axial direction, and has, in order from the side opposite the vehicle body (the left side in FIG. 1 ), a large diameter portion 22, a small diameter portion 23, and a male thread portion 24. A mounting flange portion 42 of the stator 40 is fitted and fixed to the outside of the large diameter portion 22, and a double-row angular contact ball bearing 30 is fitted and fixed to the outside of the small diameter portion 23. A signal line from a magnetic sensor 76 (described later), for example, is routed through the through hole 21 of the support shaft 20.

[0015] The double-row angular contact ball bearing 30 comprises an outer ring 31 having a pair of outer ring raceway grooves 31a on its inner peripheral surface, an inner ring 32 having a pair of inner ring raceway grooves 32a on its outer peripheral surface, a plurality of balls 33 arranged in double rows with a contact angle between the outer ring raceway groove 31a and the inner ring raceway groove 32a, and a pair of retainers (not shown) that rotatably hold the plurality of balls 33 in each row.

[0016] The inner ring 32 has an axial length L1 that is approximately the same as the axial length of the small diameter portion 23 of the support shaft 20, and has an extension portion 34 that extends from the vehicle body side end face 31b of the outer ring 31. The vehicle body side end face (axial end face) 34a of the extension portion 34, i.e., the vehicle body side end face 32b of the inner ring 32, protrudes toward the vehicle body beyond the vehicle body side end face 31b of the outer ring 31, and is approximately flush with the end face 23a of the small diameter portion 23.

[0017] The end face of the inner ring 32 of the double-row angular ball bearing 30 facing away from the vehicle body (left side in FIG. 2) abuts against the step portion 22a of the large diameter portion 22, restricting axial movement toward the side facing away from the vehicle body. Furthermore, the vehicle body side end face 32b is restricted from axial movement toward the vehicle body side (right side in FIG. 2) by a nut 25 that screws onto the male thread portion 24 via the vehicle body mounting bracket 11.

[0018] That is, the vehicle body side end surface 32b of the inner ring 32 (vehicle body side end surface 34a of the extension portion 34) cooperates with the end surface 23a of the small diameter portion 23 to form the mounting seat surface 35 of the vehicle body mounting bracket 11. As a result, even when using a support shaft 20 with strict restrictions on the inner and outer diameters, the mounting seat surface 35 has a relatively large area.

[0019] The stator 40 has a substantially annular coil portion 41 around which a coil (not shown) is wound, and a mounting flange portion 42 that protrudes from the inner peripheral surface of the coil portion 41 toward the inner diameter side and is formed integrally with the coil portion 41, and is formed with a substantially L-shaped cross section. The stator 40 is fixed to the support shaft 20 by externally fitting and fixing the mounting flange portion 42 to the large diameter portion 22.

[0020] In this way, the inner ring 32 of the double-row angular ball bearing 30 is fitted and fixed to the small diameter portion 23, and the mounting flange portion 42 of the stator 40 is fitted and fixed to the large diameter portion 22, so that the inner ring 32 of the double-row angular ball bearing 30 and the mounting flange portion 42 of the stator 40 are each fitted and fixed to the outside in line in the axial direction of the support shaft 20.

[0021] One end of the rotor 50 facing the vehicle body is supported by a support plate 61 that is fitted and fixed to the outer ring 31 of the double-row angular contact ball bearing 30. A cover plate 62 that covers the opening of the rotor 50 is provided at the other end of the rotor 50 to prevent foreign matter such as dust from entering the interior of the in-wheel motor 10. The support plate 61 and cover plate 62 have an outer peripheral surface that is larger than the outer diameter of the rotor 50, and form a wheel.

[0022] The center of the support plate 61 is tapered so as to approach the outer ring 31 in the radially inward direction, and the support shaft 20 and the extension 34 of the inner ring 32 fitted and fixed to the support shaft 20 protrude from an opening 63 formed in the center of the support plate 61. Therefore, the vehicle body mounting bracket 11 can be placed close to the support plate 61 and attached to the end face 23 a of the support shaft 20 and the vehicle body side end face 32 b of the inner ring 32 without interference, thereby reducing the axial width of the in-wheel motor 10.

[0023] Furthermore, the double-row angular contact ball bearing 30 is positioned so that an external force from the road surface acts between the pair of inner ring raceway grooves 32a and the pair of outer ring raceway grooves 31a. That is, the line of action G on which the external force from the road surface acts is located between the pair of inner ring raceway grooves 32a and the pair of outer ring raceway grooves 31a. Therefore, the axially intermediate positions of the stator 40 and the rotor 50 are located axially between the centers of the balls 33 in each row of the double-row angular contact ball bearing 30, and the road surface input from the vertical direction can be properly received.

[0024] Furthermore, a substantially annular internal space S is formed between the inner peripheral surface 41a of the coil portion 41 and the outer peripheral surface of the outer ring 31. The inner diameter side cylindrical portion 71a of a substantially disk-shaped rotating bracket 71 is fitted onto the outer peripheral surface of the outer ring 31, which rotates integrally with the rotor 50, thereby fixing the rotating bracket 71 to the outer ring 31. An encoder 72 is disposed on the side surface of the rotating bracket 71. The rotating bracket 71 and encoder 72 are positioned within the internal space S (radially outside the outer ring 31) overlapping with the outer ring 31 in the axial direction. The encoder 72 is made of a permanent magnet, and the characteristic change portion has north-pole and south-pole magnetized portions alternately and at equal intervals in the circumferential direction.

[0025] Furthermore, a notch 32c is formed at the axial end of the inner peripheral surface of the inner ring 32, and an inner diameter side cylindrical portion 75a of the fixed side bracket 75 fits into the notch 32c, thereby fixing the fixed side bracket 75 to the inner ring 32. The magnetic sensor 76 is fixed to the inner ring 32 via the fixed side bracket 75, with its detection surface facing the detected surface of the encoder 72 in the axial direction. The fixed side bracket 75 and the magnetic sensor 76 are also located within the internal space S. Therefore, the internal space S also includes the space between the inner peripheral surface 41a of the coil portion 41 on the vehicle body side of the mounting flange portion 42 and the outer peripheral surface of the large diameter portion 22 of the support shaft 20.

[0026] A magnetic detection element such as a Hall IC is incorporated into the detection surface of the magnetic sensor 76, which is arranged closely opposite the detected surface of the encoder 72. By detecting changes in the magnetic force of the encoder 72 when the encoder 72 is displaced relative to the magnetic sensor 76, the rotation signal of the encoder 72 is detected, and the rotation speed and rotation angle of the rotor 50, etc. are detected.

[0027] The magnetic sensor 76 of this embodiment uses a Hall IC, which allows for a shorter axial length compared to, for example, an MR sensor. Furthermore, by adjusting the surface area of ​​the magnet of the encoder 72, the resolution can be set to any resolution required by the traveling robot. In particular, since the encoder 72 is disposed in the internal space S provided on the outer diameter side of the outer ring 31, the radial size can be increased, which makes it easier to increase the number of poles in the characteristic change section, thereby improving the angle detection accuracy.

[0028] As described above, in-wheel motor 10 of this embodiment uses double-row angular contact ball bearing 30 as the angular contact ball bearing portion, which can stably support external forces from the road surface and extend the bearing life. Furthermore, compared to when multiple single-row bearings are used, the axial width of in-wheel motor 10 is reduced, allowing the in-wheel motor 10 to be made more compact.

[0029] Furthermore, since the encoder 72 fixed to the outer ring 31 and the magnetic sensor 76 fixed to the inner ring 32 are arranged within the internal space S, the axial width of the in-wheel motor 10 can be made compact. Furthermore, since the magnetic sensor 76 is configured using a Hall IC, the axial length can be shortened compared to when an MR sensor is used. Furthermore, the radial size of the encoder can be increased, improving the angle detection accuracy.

[0030] Furthermore, an extension 34 is provided on the inner ring 32, and the vehicle body side end face 34a of this extension 34 is used as the mounting seat 35 of the vehicle body mounting bracket 11. This makes it possible to increase the area of ​​the mounting seat 35 and prevent excessive surface pressure from the nut 25, thereby enabling the vehicle body mounting bracket 11 to be firmly and stably fixed.

[0031] When such an in-wheel motor 10 is used as a drive wheel for a self-propelled robot, a transport vehicle, or the like, with a conventional in-wheel motor 10A, the loadable area is restricted by the in-wheel motor 10A, resulting in a narrow loadable area, as shown in Figures 3(c) and (d). On the other hand, with the in-wheel motor 10 of the present embodiment, which has a reduced axial width, the loadable area is expanded, as shown in Figures 3(a) and (b), allowing for the loading of larger loads, and also enabling the load to be loaded at a low position, thereby lowering the center of gravity and enabling stable, self-sustaining driving.

[0032] Furthermore, reducing the axial width of the in-wheel motor 10 facilitates designs that comply with the robot standards of the Road Traffic Act, and contributes to the spread of traveling robots, transport vehicles, etc. by preventing accidents with pedestrians.

[0033] The present invention is not limited to the above-described embodiment, and modifications and improvements are possible as appropriate. For example, in the above embodiment, a double-row angular ball bearing was used as an example of the angular ball bearing portion, but the angular ball bearing portion is not limited to a double-row angular ball bearing, and can also be configured by arranging multiple single-row angular ball bearings in a back-to-back combination. Furthermore, although the encoder and magnetic sensor are of an axial gap type in which they face each other in the axial direction, they may be of a radial gap type in which they face each other in the radial direction.

[0034] Furthermore, although the above embodiment has been described with reference to an in-wheel motor, the sensor-equipped rolling bearing device of the present invention may be applied to other configurations as long as it is configured to include at least an angular ball bearing portion, an encoder, and a magnetic sensor, and the above-mentioned effects can also be achieved as a sensor-equipped rolling bearing device.

[0035] As described above, the present specification discloses the following: (1) An angular contact ball bearing unit comprising an outer ring having a raceway surface on its inner peripheral surface, an inner ring having a raceway surface on its outer peripheral surface, and a plurality of balls disposed so as to roll freely between the raceway surfaces of the outer ring and the inner ring, and used for outer ring rotation, the angular contact ball bearing unit being composed of a double-row angular contact ball bearing or a plurality of angular contact ball bearings; an encoder fixed to the outer ring on the radially outer side of the outer ring; a magnetic sensor fixed to the inner ring via a fixed-side bracket radially outward of the outer ring so as to face the encoder, and configured to detect the rotational speed of the outer ring; Rolling bearing device with sensor. According to this configuration, the encoder and the magnetic sensor can be handled as a single unit with the angular ball bearing portion, which contributes to miniaturization and improved ease of handling. Furthermore, when applied to an in-wheel motor, the width of the in-wheel motor can be slimmed down, making it possible to miniaturize the running robot, preventing collisions with pedestrians and contributing to the spread of running robots.

[0036] (2) a support shaft onto which the inner ring of the angular ball bearing portion is fitted and fixed, and which is fastened to a vehicle body and does not rotate; a stator having an attachment flange portion that is fitted and fixed to the outside of the support shaft so as to be aligned with the inner ring in the axial direction of the support shaft; a rotor supported by a support plate fitted and fixed to the outer ring of the angular ball bearing and disposed rotatably relative to the stator; Equipped with the encoder and the magnetic sensor are disposed in an internal space provided between an inner peripheral surface of the stator and an outer peripheral surface of an outer ring of the angular ball bearing. The sensor-equipped rolling bearing device according to (1). According to this configuration, by arranging the encoder and magnetic sensor in the internal space provided between the inner surface of the stator and the outer surface of the outer ring, the encoder and magnetic sensor can be detected with an accuracy greater than the resolution of the number of motor magnet poles, and the internal space can be utilized to achieve miniaturization.

[0037] (3) The inner ring of the angular ball bearing has an extension extending from an axial end face of the outer ring, and the axial end face of the extension forms a seat surface to be fastened to the vehicle body. The sensor-equipped rolling bearing device according to (2). According to this configuration, the inner ring can secure the necessary area for the seat surface for fastening to the vehicle body, improving the connection strength with the vehicle body and facilitating installation on the vehicle body.

[0038] (4) The encoder is fixed to the outer ring by fitting an inner diameter cylindrical portion of a rotating bracket to an outer peripheral surface of the outer ring. The sensor-equipped rolling bearing device according to (1). With this configuration, the encoder can be reliably fixed to the outer ring.

[0039] (5) The magnetic sensor is fixed to the inner ring by fitting an inner diameter side cylindrical portion of the fixed side bracket into a notch formed on the inner peripheral surface of the inner ring. The sensor-equipped rolling bearing device according to (1). With this configuration, the magnetic sensor can be reliably fixed to the inner ring.

[0040] (6) An axially intermediate position of the stator and the rotor is located between the centers of the balls in each row of the angular ball bearing portion in the axial direction. The sensor-equipped rolling bearing device according to (1). According to this configuration, road surface input from the vertical direction can be properly received, and the life of the angular ball bearing portion is improved.

[0041] (7) The angular ball bearing portion is constituted by a double-row angular ball bearing. The sensor-equipped rolling bearing device according to (1). According to this configuration, the axial width can be reduced compared to when a plurality of single-row angular contact ball bearings are used. [Explanation of symbols]

[0042] 10 In-wheel motor 20 Support shaft 30 Double-row angular contact ball bearing (angular contact ball bearing part) 31 outer ring 31a Outer ring raceway groove (raceway surface) 31b Car body side end face (axial end face of outer ring) 32 Inner circle 32a Inner ring raceway groove (raceway surface) 32c notch 33 balls 34 Extension 34a Body side end face (axial end face of extension part) 35 seat 40 Stator 41a Inner surface of stator 42 Mounting flange 50 rotors 61 Support plate 71 Rotating side bracket 71a Inner diameter cylindrical part 72 Encoder 75 Fixed side bracket 75a Inner diameter cylindrical part 76 Magnetic Sensor S interior space

Claims

1. an angular contact ball bearing section comprising an outer ring having a raceway surface on its inner peripheral surface, an inner ring having a raceway surface on its outer peripheral surface, and a plurality of balls rollably disposed between the raceway surfaces of the outer ring and the inner ring, the angular contact ball bearing section being used for outer ring rotation and being composed of a double-row angular contact ball bearing or a plurality of angular contact ball bearings; an encoder fixed to the outer ring on the radially outer side of the outer ring; a magnetic sensor fixed to the inner ring via a fixed-side bracket radially outward of the outer ring so as to face the encoder, and configured to detect the rotational speed of the outer ring; Rolling bearing device with sensor.

2. a support shaft onto which the inner ring of the angular ball bearing portion is fitted and fixed, and which is fastened to a vehicle body and does not rotate; a stator having an attachment flange portion that is fitted and fixed to the outside of the support shaft so as to be aligned with the inner ring in the axial direction of the support shaft; a rotor supported by a support plate fitted and fixed to the outer ring of the angular ball bearing and disposed rotatably relative to the stator; Equipped with the encoder and the magnetic sensor are disposed in an internal space provided between an inner peripheral surface of the stator and an outer peripheral surface of an outer ring of the angular ball bearing.

2. The sensor-equipped rolling bearing device according to claim 1.

3. an inner ring of the angular ball bearing portion has an extension portion extending from an axial end surface of the outer ring, and the axial end surface of the extension portion forms a seat surface to be fastened to the vehicle body; 3. The sensor-equipped rolling bearing device according to claim 2.

4. The encoder is fixed to the outer ring by fitting an inner diameter side cylindrical portion of a rotation side bracket to an outer peripheral surface of the outer ring.

2. The sensor-equipped rolling bearing device according to claim 1.

5. the magnetic sensor is fixed to the inner ring by fitting an inner diameter cylindrical portion of the fixed bracket into a notch formed in an inner peripheral surface of the inner ring; 2. The sensor-equipped rolling bearing device according to claim 1.

6. an axially intermediate position of the stator and the rotor is located axially between the centers of the balls in each row of the angular ball bearing portion; 2. The sensor-equipped rolling bearing device according to claim 1.

7. The angular ball bearing portion is constituted by a double-row angular ball bearing.

2. The sensor-equipped rolling bearing device according to claim 1.

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